1. Field of the Invention
The present invention relates to a method of manufacturing an all-in-one type light guide plate.
2. Description of the Related Art
Backlight apparatuses illuminate flat panel display apparatuses, such as liquid crystal display apparatuses. Backlight apparatuses can be classified as direct light or light guide type backlight apparatuses, according to the position of the light sources. Light guide type backlight apparatuses are further classified as flat or wedge type backlight apparatuses.
Direct light type is a surface emission method that disposes a light source directly under a light emitting surface. A plurality of light sources can be disposed to improve the brightness and increase the light emission area. However, if power consumption increases, and if the backlight apparatus becomes thin, uniformity of the light is degraded, and thus, it is difficult to make the backlight apparatus thin.
The light guide type uses a light guide plate for guiding a ray to a light emitting surface, and the light source is disposed on a side surface of the light guide plate. A length of the side surface of the light guide plate limits the number of light sources, and thus, the backlight apparatus is thin. However, a process for distributing the brightness, throughout the entire light emitting surface, is complex.
The flat type, which is a type of light guide type backlight apparatus, is used in monitors or in cases requiring a high brightness. Light sources can be fixed on both sides or four corners of the light guide plate, and a plurality of light sources is used in order to increase the brightness. A side thickness of the light guide plate must also be uniform.
The wedge type, which is another type of light guide type backlight apparatus, is used in apparatuses where a plurality of light sources cannot be used due to limited power consumption, such as notebook computers. A surface, through which a light source is induced, of the backlight apparatus has a large width, and the other surface has a narrow width to reduce a backlight's weight.
A line light source and a point light source can be used as light sources in the light guide type backlight apparatus. The line light source can be a cold cathode fluorescent lamp (CCFL), having electrodes on both ends installed in a pipe. The point light source can be a light emitting diode (LED). The CCFL can emit an intense white light, obtain high brightness, and has high uniformity within a large area. However, the CCFL is driven by radio frequency alternating current (AC) signals, and operates within a small temperature range. The LED has lower brightness and lower uniformity when compared to the CCFL. However, the LED is driven by direct current (DC) signals, has a long lifespan, and operates within a wide temperature range. In addition, the LED is thin.
FIG. 1 is a side sectional view of a side emission type backlight apparatus, according to the conventional art.
Referring to FIG. 1, line light sources 10 are disposed on both side surfaces 21 and 22 of a light guide plate 20. A light path changing unit 23 is formed on a lower surface of the light guide plate 20 to discharge the light, incident from the line light sources 10, towards a light emitting surface 24.
A plurality of inverse-prism shape structures 30 are disposed on an upper surface of the light guide plate 20 to diffuse the light emitted from the light emitting surface 24. The inverse-prism shape structures 30 are fixed on the upper surface of the light guide plate 20 using an adhesive layer 32.
The light incident into the light guide plate 20, from the line light sources 10, is emitted through the light emitting surface 24, of the light guide plate 20, by the light path changing unit 23. The light incident then spreads to the upper portion of the light guide plate 20 by the inverse-prism shape structures 30, after passing through the adhesive layer 32.
However, since the inverse-prism shape structures 30 are fixed on the upper surface of the light guide plate 20, by the adhesive layer 32, the light incident into the inverse-prism shape structures 30 must pass through the adhesive layer 32. The adhesive layer 32 interferes and affects the quality of the light. Therefore, the adhesive layer 32 is not advantageous because the performance of the inverse-prism shape structures 30 is determined by the degree of adhesion in the adhesive layer 32.
In order to solve the problem stated above, an all-in-one type light guide plate, in which the inverse-prism shape structure is integrally formed with the light guide plate, has been provided. In order to form the all-in-one type light guide plate, a master, in which the shape of the all-in-one type light guide plate is molded, is fabricated A material is filled into the master, and then separated to form the all-in-one type light guide plate.
According to this method, since the master becomes a mold, in order to form a plurality of molds, the fabrication of the master must be repeated many times.